Portable communication units have become increasingly popular in recent years. Use of portable cellular telephones, for example, has become widespread. This increasing use of portable communication units is largely traceable to improvements in both circuit miniaturization and battery technology.
Circuit miniaturization has led to construction of portable units that are small in size while offering performance that rivals that of mobile units (generally designed for vehicle mounting rather than being carried on the person). Improvements in battery technology have led to improvements in portable unit output power, talk time, and standby time. As is well-known, talk time refers to battery life while both transmitter and receiver portions of a portable unit are in operation, while the term standby time is related to battery life while the receiver portion is active and the transmitter is inactive.
Of course, most users prefer rechargeable batteries so that the portable unit (or its battery pack alone) can simply be placed in a charger for a period of time to restore the batteries to a fully charged state. This is much simpler and more economical than replacing batteries every time battery voltage falls below a useful level.
Battery chargers generally fall into two categories; rapid chargers and trickle chargers. A rapid charger charges a battery at a relatively high current, achieving full charge in a relatively short period of time. A trickle charger, on the other hand, charges battery cells using a very small current, and consequently takes substantially longer to restore a battery to full charge.
Since rapid chargers subject batteries undergoing recharging to relatively high currents, there is some risk of battery cell damage should the operation be conducted improperly. Several techniques are known in the art for conducting recharging operations based upon distinct sets of charging parameters. For example, batteries may be recharged by monitoring cell temperature and controlling charging current with reference to peak temperature or rate of temperature rise. Battery voltage is monitored during different stages of the recharging cycle according to other techniques. Even rate of voltage change can be a useful parameter in some charging methodologies. Of course, the need for different charging techniques is at least partially driven by changes in battery, technology. Although nickel cadmium rechargeable cells are well-known, nickel metal hydride cells are also in use, as well as lithium batteries.
A sophisticated rapid charger should be able to cope with a mixture of battery technologies and charging regimens. Of course, to do this, the rapid charger would require the ability to identify battery type as well as to make appropriate measurements of temperature, voltage, etc. To handle this degree of complexity, a microprocessor is generally included as part of the recharger circuitry.
Trickle chargers, on the other hand, are often inexpensive alternatives to sophisticated rapid chargers. Instead of employing a microprocessor, simple discrete components within the trickle charger generate the appropriate low charging current when a predetermined component within the battery module to be charged completes an electrical connection with the trickle charger circuitry. Present trickle chargers, largely due to their inherent lack of sophistication, are generally compatible with only one or two battery types. Rapid chargers, of course, because of their microprocessor construction, have sufficient flexibility to detect many battery types and provide a suitable charging environment.
In order to avoid the necessity of constructing a myriad different types of trickle chargers to accommodate different battery types, a need arises for a battery module that provides flexible connections of interior components that can be detected easily by either sophisticated rapid chargers or less sophisticated trickle chargers.